1. Field of the Invention
The present invention relates to the field of couplings between rotating shafts and in particular relates to improvements in flexible couplings between shafts whereby the shafts may continue to be driven even though the flexible coupling means between the shafts fails.
2. Description of the Prior Art
Flexible couplings are used in mechanical applications wherever two shafts need to be coupled and are not precisely coaxial at all times. One of the primary applications where this occurs is where there is a substantial amount of vibration, such as in vehicles and, in particular, in aircraft.
In an aircraft application not only are vibrational stresses particularly exaggerated, but all elements of the shaft and coupling must be extremely light weight and yet capable of carrying extremely high loads with a very high reliability. One of the flexible couplings used throughout aircraft is a "Bendix coupling" manufactured by the Bendix Corporation, one example which is illustrated in the drawings and which is sold and distributed as Bendix Model No. 19E111-1 and 19E149.
In the case where a flexible coupling is used to couple two shafts used in the power train in a helicopter, it is extremely important that the coupling has a high degree of reliable performance in a very adverse environment. Where the flexible coupling is used in the shaft which drives the tail rotor in a helicopter, it is important that power be delivered to the tail rotor at all times without interruption. Should power delivery to the tail rotor be lost, serious consequences may arise by the unexpected loss of control.
Therefore, what is needed is a lightweight and extremely reliable means whereby an improvement can be made in a flexible coupling used between two shafts whereby the shaft will be securely driven or engaged notwithstanding the failure of the coupling.